[Responsibilities of Weaning Centers during the COVID-19 Pandemic Outbreak - Recommendations for the Assignment of ICU Capacities in COVID-19 Patients as shown by the Berlin-Brandenburg POST-SAVE-Model]

Die enorme Zunahme von Patienten mit schwerer respiratorischer Insuffizienz aufgrund der COVID19-Pandemie erfordert einen systematischen Ansatz zur Optimierung der Betreuung von beatmeten Patienten. Ein standardisierter Algorithmus namens „SAVE“ wurde in Berlin entwickelt, um Patienten mit COVID-19-Infektion, die eine invasive Beatmung benötigen, zu lenken. Um Bettenkapazitäten auf den Intensivstationen sicherzustellen, muss eine konstante Patientenentlassung gewährleistet sein. Ein strukturierter Entlassungsprozess der Patienten nach der Akutbehandlung ist dringend erforderlich.

In einem nächsten Schritt haben wir einen Triage-Algorithmus entwickelt, um Patienten auf SAVE-Intensivstationen zu identifizieren, die das Potenzial haben, von der Beatmung entwöhnt zu werden und in dafür spezialisierte Einrichtungen zu verlegen. Dieser Prozess ist das POST-SAVE-Konzept.

In der vorliegenden Arbeit werden die Algorithmen dargestellt, einschließlich der Verwendung einer standardisierten digitalen Datenbank, der Verwendung geschulter Lotsen zur Erleichterung der Kommunikation zwischen SAVE-Intensivstationen und Weaningeinheiten und der Etablierung eines prospektiven Datenregisters, um Patienten dauerhaft hinsichtlich ihres Weaningpotenzials reevaluieren zu können.

First case of hepatitis C virus transmission by a red blood cell concentrate after introduction of nucleic acid amplification technique screening in Germany: a comparative study with various assays

BACKGROUND AND OBJECTIVES

Pooled nucleic acid amplification techniques (NAT) and donor screening for anti-hepatitis C virus (HCV) have reduced the diagnostic window period of HCV infection in the blood donor population from about 12 to 1 or 2 weeks. During that time, HCV RNA is hardly detectable by pooled or individual donation NAT. Here we describe a case of transfusion-acquired HCV infection from an extremely low-titre donation. After a repeat donor tested positive for HCV, a look-back procedure was initiated. A recipient of a red cell concentrate from the previous donation was identified and found to be infected with HCV as well. We compared several commercial NAT systems for their ability to detect the viraemic plasma.

MATERIALS AND METHODS

Molecular analyses of HCV in donor and recipient samples were performed. The HCV-transmitting plasma was tested using different commercially available qualitative and quantitative NAT assays.

RESULTS

HCV transmission was verified by molecular analyses and was assigned to genotype 2b. NAT with various commercial HCV assays detected the infection erratically in individual donations. However, the detection rate was not directly related to the claimed sensitivity of some HCV NATs.

CONCLUSIONS

HCV transmission can be caused by donations that escape NAT detection even when tested in an individual donation. Comparison of different assays led to results that did not necessarily reflect the expected sensitivities. The need for standard materials representing further HCV genotypes is discussed.

Effects of extended storage of whole blood before leucocyte depletion on coagulation factors in plasma

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate the quality of leucocyte-depleted plasma produced from leucocyte-depleted whole blood, stored for different periods of times before filtration through polyurethane filters.

MATERIALS AND METHODS

Whole blood was collected, from 48 voluntary donors, into quadruple blood bag sets with integrated whole-blood filters, and stored at room temperature for 1, 2, 6, or 18 h before filtration. Five samples were taken: one directly from the donor; one immediately after collection; one before and one after filtration; and one from plasma units before freezing. All samples were analysed for the following parameters: prothrombin time; activated partial thromboplastin time; prothrombin fragments F1+2; fibrinogen; factors VIII, XI and XII; von Willebrand factor antigen; ristocetin cofactor activity; collagen-binding capacity; multimers; and complement C3a-desArg.

RESULTS

Different whole-blood storage times before filtration did not have a significant effect on the stability of coagulation factors. The activity of all investigated coagulation factors in plasma was generally above 90 U/dl, even after 18 h of storage of whole blood before filtration. von Willebrand factor multimeric distribution remained stable throughout the process. However, activation of complement did occur during storage.

CONCLUSIONS

Leucodepleted plasma originating from leucodepleted whole blood maintains a satisfactory level of coagulation factors, even after the storage of whole blood for 18 h at room temperature before filtration.

Rapid genotyping of human platelet antigen 5 with fluorophore-labelled hybridization probes on the LightCycler

Genotyping of human platelet antigens (HPAs) can be useful for the diagnosis and therapy of alloimmune thrombocytopenic syndromes such as neonatal alloimmune thrombocytopenic purpura, post-transfusion purpura and refractoriness to platelet transfusion therapy. We developed a single-tube method for HPA-5 genotyping on the LightCycler that combines rapid-cycle polymerase chain reaction with allele-specific fluorescent probe melting for mutation detection. Our method is fast, robust and suitable for routine HPA-5 typing. This work extends recent studies on HPA-1 typing using the LightCycler.

Vaccination with a recombinant vesicular stomatitis virus expressing an influenza virus hemagglutinin provides complete protection from influenza virus challenge

Since the development of a system for generating vesicular stomatitis virus (VSV) from plasmid DNAs, our laboratory has reported the expression of several different glycoproteins from recombinant VSVs. In one of these studies, high-level expression of an influenza virus hemagglutinin (HA) from a recombinant VSV-HA and efficient incorporation of the HA protein into the virions was reported (E. Kretzschmar, L. Buonocore, M. J. Schnell, and J. K. Rose, J. Virol. 71:5982-5989, 1997). We report here that VSV-HA is an effective intranasal vaccine vector that raises high levels of neutralizing antibody to influenza virus and completely protects mice from bronchial pneumonia caused by challenge with a lethal dose of influenza A virus. Additionally, these recombinant VSVs are less pathogenic than wild-type VSV (serotype Indiana). This vector-associated pathogenicity was subsequently eliminated through introduction of specific attenuating deletions. These live attenuated recombinant VSVs have great potential as vaccine vectors.

Biosynthesis, intracellular transport and enzymatic activity of an avian influenza A virus neuraminidase: role of unpaired cysteines and individual oligosaccharides

Intracellular transport, glycosylation, tetramerization and enzymatic activity of the neuraminidase (NA) of fowl plague virus (FPV) were analysed in vertebrate cells after expression from a vaccinia virus vector. Tetramerization occurred with a half-time of 15 min, whereas passage through the medial Golgi apparatus and transport to the plasma membrane occurred with half-times of 2 and 3 h, respectively, suggesting a step in NA maturation beyond tetramerization that limits the rate of transport to the medial Golgi. NA transport rates were about fourfold slower than those of haemagglutinin (HA). Slow transport and processing of FPV NA was not altered by coexpression of FPV HA, nor was the transport rate of HA influenced by NA. The slow transport kinetics of NA were also observed in FPV-infected CV-1 cells. As deduced from the coding sequence, FPV NA has the shortest stalk of all naturally occurring NAs described to date and contains only three potential N-glycosylation sites, which are all located in the globular head domain. Elimination of each of the three N-glycosylation sites revealed that the two oligosaccharides at positions 124 and 66 are of the complex type, whereas the one at Asn-213 remains in mannose-rich form. The glycosylation mutants showed also that oligosaccharides at positions 124 and 213 of FPV NA modulate enzymatic activity. Transport of NA is not influenced by single elimination of any of the three oligosaccharide attachment sites. Mutational analysis of the three Cys residues not involved in intrachain disulfide pairing revealed that Cys-49 in the stalk of the NA molecule is responsible for the formation of disulfide-linked dimers. Analysis of cysteine mutants of FPV NA also demonstrated that disulfide-linked dimers are not absolutely necessary for the formation of enzymatically active tetramers but may stabilize the quaternary structure of NA.

High-efficiency incorporation of functional influenza virus glycoproteins into recombinant vesicular stomatitis viruses

We derived recombinant vesicular stomatitis virus (VSV) expressing either influenza virus hemagglutinin (HA) or neuraminidase (NA) glycoproteins from extra genes inserted in the viral genome. The HA protein was expressed from a site downstream of the VSV glycoprotein (G) gene, while NA protein was expressed from a site upstream of the VSV G gene. The HA protein was expressed at lower levels than the VSV G protein, while the NA protein was expressed at higher levels, as expected from the gradient of VSV transcription that follows the gene order. The HA and NA proteins were transported to the cell surface and were functional as demonstrated by hemadsorption, hemolysis, and NA assays. Biochemical analysis showed that both HA and NA proteins were incorporated into VSV particles at high levels, although there was a preference for incorporation of the VSV G protein over either of the influenza virus proteins. Immunoelectron microscopy of the recombinants showed that the particles derived from the recombinants were mosaics carrying both the VSV G protein and the influenza virus membrane glycoproteins. These results extend earlier studies showing incorporation of the cellular glycoprotein CD4 and two other viral glycoproteins into VSV particles. Our results indicate that there is significant space in the VSV membrane that can accommodate foreign membrane proteins and that the foreign protein can represent as much as 35% of the total protein in the viral envelope. Incorporation of foreign proteins into VSV virions can, in many cases, occur passively in the absence of specific incorporation signals.

Foreign glycoproteins expressed from recombinant vesicular stomatitis viruses are incorporated efficiently into virus particles

In a previous study we demonstrated that vesicular stomatitis virus (VSV) can be used as a vector to express a soluble protein in mammalian cells. Here we have generated VSV recombinants that express four different membrane proteins: the cellular CD4 protein, a CD4-G hybrid protein containing the ectodomain of CD4 and the transmembrane and cytoplasmic tail of the VSV glycoprotein (G), the measles virus hemagglutinin, or the measles virus fusion protein. The proteins were expressed at levels ranging from 23-62% that of VSV G protein and all were transported to the cell surface. In addition we found that all four proteins were incorporated into the membrane envelope of VSV along with the VSV G protein. The levels of incorporation of these proteins varied from 6-31% of that observed for VSV G. These results suggest that many different membrane proteins may be co-incorporated quite efficiently with VSV G protein into budding VSV virus particles and that specific signals are not required for this co-incorporation process. In fact, the CD4-G protein was incorporated with the same efficiency as wild type CD4. Electron microscopy of virions containing CD4 revealed that the CD4 molecules were dispersed throughout the virion envelope among the trimeric viral spike glycoproteins. The recombinant VSV-CD4 virus particles were about 18% longer than wild type virions, reflecting the additional length of the helical nucleocapsid containing the extra gene. Recombinant VSVs carrying foreign antigens on the surface of the virus particle may be useful for viral targeting, membrane protein purification, and for generation of immune responses.

Membrane association of influenza virus matrix protein does not require specific hydrophobic domains or the viral glycoproteins

The matrix protein of influenza virus is a major structural component of the virion which is generally believed to bridge between the membrane envelope and the ribonucleocapsid core. To investigate the interaction of M1 with cellular membranes in the absence of other influenza proteins, we examined its distribution by subcellular fractionation after expression in HeLa cells. Approximately 81 to 88% of M1 protein, expressed without other viral proteins, was soluble, whereas the remaining 12 to 19% was tightly associated with membranes. Conditions known to release peripherally associated membrane proteins did not detach M1 proteins from isolated membranes, suggesting that the fraction of M1 bound to membranes behaves as an integral protein. Coexpression of M1 with hemagglutinin or neuraminidase did not alter the extent of membrane association of M1 protein, indicating that there is no strong interaction between M1 and the cytoplasmic tails of the viral glycoproteins. Additional attempts were made to identify membrane binding domains in M1 protein. Mutants constructed with mutations in the four hydrophobic regions thought to be responsible for membrane association still exhibited the same levels of membrane association as that observed with wild-type matrix protein. Therefore, specific hydrophobic domains are apparently not required for membrane binding.

Elongation of the N-glycans of fowl plague virus hemagglutinin expressed in Spodoptera frugiperda (Sf9) cells by coexpression of human beta 1,2-N-acetylglucosaminyltransferase I

Spodoptera frugiperda (Sf9)-cells differ markedly in their protein glycosylation capacities from vertebrate cells in that they are not able to generate complex type oligosaccharide side chains. In order to improve the oligosaccharide processing properties of these cells we have used baculovirus vectors for expression of human (beta 1,2-N-acetylglucosaminyltransferase I (hGNT-I), the enzyme catalysing the crucial step in the pathway leading to complex type N-glycans in vertebrate cells. One vector (Bac/GNT) was designed to express unmodified GNT-I protein, the second vector (Bac/tagGNT) to express GNT-I protein with a tag epitope fused to its N-terminus. In Sf9-cells infected with Bac/tagGNT-virus a protein of about 50 kDa representing hGNT-I was detected with an antiserum directed against the tag epitope. HGNT-I activity was increased at least threefold in lysates of infected cells when N-acetylglucosamine (GlcNAc)-free ovalbumine was used as substrate. To monitor hGNT-I activity in intact Sf9-cells, the glycosylation of coexpressed fowl plague virus hemagglutinin (HA) was investigated employing a galactosylation assay and chromatographic analysis of isolated HA N-glycans. Coexpression of hGNT-I resulted in an at least fourfold increase of HA carrying terminal GlcNAc-residues. The only structure detectable in this fraction was GlcNAcMan3GlcNAc2. These results show that hGNT-I is functionally active in Sf9-cells and that the N-glycans of proteins expressed in the baculovirus/insect cell system are elongated by coexpression of glycosyltransferases of vertebrate origin. Complete complex type oligosaccharide side chains were not observed when hGNT-I was overexpressed, thus supporting the concept that Sf9-cells do not contain glycosyltransferases acting after hGNT-I.

Normal replication of vesicular stomatitis virus without C proteins

The expression of two small basic proteins (C and C') encoded by a second open reading frame of the New Jersey serotype of vesicular stomatitis virus (VSV) P gene was reported previously (Spiropoulou and Nichol, J. Virol., 67, 3103-3110, 1993). Here we found that the Indiana serotype virus also expressed C and C' proteins from this reading frame. We eliminated C and C' expression by making a single base change that introduced a stop codon in the C and C' coding sequence, but left the P-protein sequence unchanged. This mutated P gene supported normal replication and packaging of VSV minigenomes encoding G and M proteins. The mutated P gene was also recombined into an infectious clone of VSV that was used to recover virus. The mutant virus no longer expressed the C and C' proteins but showed growth kinetics identical to wild-type virus. The amounts of viral mRNAs and proteins synthesized were indistinguishable in mutant and wild-type virus infected cells as were the yields and composition of mutant and wild-type virus particles. The kinetics of host protein-synthesis shut-off were also identical for both viruses. Although the C and C' proteins were dispensable for VSV growth in tissue culture, they are known to be conserved in all vesiculoviruses, and thus perhaps play a role in viral pathogenesis or transmission by insect vectors.

N1 neuraminidase of influenza virus A/FPV/Rostock/34 has haemadsorbing activity

The neuraminidase (NA) gene of influenza virus A/FPV/Rostock/34 virus (H7N1) was cloned and expressed in Sf9 cells using a baculovirus vector. The expression product had the expected molecular mass and showed neuraminidase activity. NA expressed in Sf9 cells also showed haemagglutinating activity as indicated by its ability to induce haemadsorption of chicken red blood cells. Haemadsorption depended on the presence of neuraminic acid on the erythrocytes, but was not blocked by 2-deoxy-2,3-dehydro-N-acetylneuraminic acid, a specific inhibitor of the enzymatic activity. These observations suggest that the N1 neuraminidase has two distinct reactive sites: a catalytic site and a receptor binding site. This concept was confirmed by site-directed mutagenesis which showed that the haemadsorbing activity of FPV NA was abolished when amino acids located on two surface loops at the putative binding site were exchanged. Substitutions on either of the two loops were sufficient for this effect. The mutated NAs retained full neuraminidase activity. In contrast, a mutated NA lacking neuraminidase activity still had haemadsorbing activity.

Carbohydrate masking of an antigenic epitope of influenza virus haemagglutinin independent of oligosaccharide size

Comparison of the haemagglutinins (HA) of the pathogenic avian influenza viruses A/FPV/Dutch/27 (H7N7) and A/FPV/Rostock/34 (H7N1) revealed 94.7% nucleotide and 93.8% amino acid sequence homologies. Six of the seven N-glycosidic oligosaccharides of the Rostock HA are at the same positions as the six carbohydrates of the Dutch strain. The additional oligosaccharide side chain of the Rostock strain, which is of the complex type, is attached to asparagine149 in antigenic epitope B. The accessibility of this antigenic epitope has been analysed by using rabbit antisera raised against synthetic peptides comprising amino acids 143-162. The carbohydrates of the HA of the Rostock strain have been modified (i) to truncated cores by expression in insect cells using a baculovirus vector, (ii) to oligomannosidic side chains by growth in the presence of the trimming inhibitor methyldeoxynojirimycin and (iii) to a single N-acetylglucosamine residue by removal of the oligomannosidic sugar with endo-beta-N-acetylglucosaminidase H. Neither the authentic nor the modified oligosaccharides allowed antibody binding, as indicated by enzyme-linked immunosorbent assay (ELISA) and Western blot analyses. Reactivity was observed, however, after complete removal of the carbohydrate from HA of the Rostock strain by digestion with peptide-N-glycosidase F. HA of the Dutch strain was reactive without prior peptide-N-glycosidase F treatment. These results demonstrate that a single N-acetyl-glucosamine at asparagine149 is sufficient to prevent recognition of the peptide epitope.

Secretion of fowl plague virus haemagglutinin from insect cells requires elimination of both hydrophobic domains

In the present study we have investigated the role of the hydrophobic domains of the fowl plague virus (FPV) haemagglutinin (HA) on its intracellular transport and maturation in insect cells. To this end processing of full-length HA (A+) has been compared to that of two truncated forms lacking either the cytoplasmic domain and the transmembrane domain (A-) or lacking the entire HA2 subunit, i.e. the transmembrane domain and the fusion peptide (HA2-). All glycosylation sites present on A- and HA2- were glycosylated, indicating that both truncated forms were completely translocated in the endoplasmic reticulum. Unlike A+, A- and HA2- did not form trimers as indicated by cross-linking, gradient centrifugation and studies employing conformation-specific antibodies. Whereas HA2- was efficiently secreted, A- was retained in the cells in an apparently membrane-bound form. The data show that the carboxy-terminal transmembrane region is essential for the formation and stability of the trimers of the FPV HA. These observations also indicate that, under certain conditions, the fusion peptide of the FPV HA can serve as a membrane anchor.

Site-specific mutagenesis identifies three cysteine residues in the cytoplasmic tail as acylation sites of influenza virus hemagglutinin

The hemagglutinin (HA) of influenza virus is a type I transmembrane glycoprotein which is acylated with long-chain fatty acids. In this study we have used oligonucleotide-directed mutagenesis of cloned cDNA and a simian virus 40 expression system to determine the fatty acid binding site in HA and to examine possible functions of covalently linked fatty acids. The results show that the HA is acylated through thioester linkages at three highly conserved cysteine residues located in the cytoplasmic domain and at the carboxy-terminal end of the transmembrane region, whereas a cysteine located in the middle of the membrane-spanning domain is not acylated. Mutants lacking fatty acids at individual or all three attachment sites acquire endoglycosidase H-resistant oligosaccharide side chains, are cleaved into HA1 and HA2 subunits, and are transported to the plasma membrane at rates similar to that of wild-type HA. All mutants are membrane bound and not secreted into the medium. These results exclude transport signal and membrane-anchoring functions of covalently linked fatty acids for this integral membrane glycoprotein. Furthermore, lack of acylation has no obvious influence on the biological activities of HA: cells expressing fatty acid-free HA bind to and, after brief exposure to mildly acidic pH, fuse with erythrocytes; the HA-induced polykaryon formation is not impaired, either. Other possible functions of covalently linked fatty acids in integral membrane glycoproteins which cannot be examined in conventional cDNA expression systems are discussed.

The structure of serotype H10 hemagglutinin of influenza A virus: comparison of an apathogenic avian and a mammalian strain pathogenic for mink

The primary structure of the hemagglutinin of the apathogenic avian influenza virus A/chick/Germany/N/49 (H10N7) and of the serologically related strain A/mink/Sweden/84 (H10N4) pathogenic for mink has been elucidated by nucleotide sequence analysis, and the carbohydrates attached to the polypeptide have been determined. The H10 hemagglutinin has 65, 52, 46, 45, and 44% amino acid sequence homology with serotypes H7, H3, H1, H2, and H5, respectively. H10 and H7 hemagglutinins are also most closely related in their glycosylation patterns. There is a high sequence homology between both H10 strains supporting the concept that the mink virus has obtained its hemagglutinin from an avian strain. The sequence homology includes the cleavage site which consists of a single arginine as is the case with most other hemagglutinins exhibiting low susceptibility to proteolytic activation. The similarity in hemagglutinin structure between both H10 strains is discussed in light of the distinct differences in the pathogenicity of both viruses.

[Cardioselective beta receptor blockade in acute myocardial infarct with talinolol]

On 9 patients with acute myocardial infarction the influence of talinolol (cordanum) on haemodynamic parameters in intravenous administration and after this in oral application was examined. Talinolol led to a slight decrease of the heart rate, of the arterial blood pressure and of the cardiac output as well as to a more distinct reduction of the contractility in nearly uninfluenced left-ventricular filling pressure. In comparison to a conventionally treated control group (n = 11) the decrease of the heart rate as well as of the contractility was somewhat more distinct. The changes found are to be explained in the sense of a heart exoneration. In one patient possibly by talinolol a deterioration of the pumping function developed 56 hours after the acute event. In another patient a depressive effect on the sinus node is not to be excluded. Ventricular fibrillation and disturbances of the atrioventricular conduction did not appear in contrast to the control group. The influence on supraventricular and ventricular cardiac dysrhythmias was distinctly favourable in other 9 patients with acute myocardial infarction despite clinical signs of cardiac decompensation. Only in one patient a further deterioration of the pumping function developed despite control of the disturbance of rhythm. According to the experimental and up to now existing clinical experiences beta-receptor blockers are indicated above all in the early phase of the acute myocardial infarction, if shock, acute heart insufficiency and bradycardiac disturbances of the heart rhythm are not existing. Here paticularly at the beginning of the therapy is a proved change in the first 2-4(-8) hours to prevent the expansion of the infarct size or the onset of large infarctions.